I prefer the foam, but you have to have water in the tub or the foam may lift it off the base.

: I was wondering can you use the spray foam to set a whirlpool tub on, instead of motar. The plumber have connected all the pluming for my whirlpool tub but he did not set it on top of motar, he want to use the foam spray that expands and get hard. Will my tub crack if motar is not used? Have anyone ever did this and regretted it later?